Just think of all the software infrastructure you rely on is probably running COBOL or very, very old tech, you
really don't want those to be re-written today. Also, the industry (think CNC controllers) relies on tried and true interfaces that are just unavailable today (USB is utter rubbish in high electrical noise environment) and there is barely replacement either. Not to mention the cost of training blue-collars operators...
Real world is not the web cocoon, even there, switching front-end every 2 years is not acceptable.
disclamer: I know that for a fact as I'm in the process of replacing a CNC control system with modern parts, trust me it's HARD.